Notes: Administrivia: Class location will change to a classroom, check webpage for updates! This class is P/NP, like all decal/seminar classes Check out the Scripting with Perl decal course if you're interested in learning more thoroughly about scripting. If you didn't write your SID on the sign-in sheet, and you are enrolled, email me so I know who is actually taking the class. Course Notes: What is Unix? How can one learn about system administration? Summary: It's not hard, but experience is the best teacher. What are the goals for the class? Show you enough that you can install and configure a linux box at home to be your router, firewall, and personal webserver. To build a foundation with which you could get a job as a student sysadmin. Students requested that we touch on security and scripting. Recommended Books: My favorite general-purpose book is Unix System Administration Handbook by Nemeth, Snyder, Seebass and Hein. This was the "red-book" that I held up in class. Now in it's third edition (and has changed to a purple cover), this book provides excellent coverage of routine system administration tasks. The other great reference book is Unix Power Tools, which provides an easy reference to nearly all the common commands you might use as a user or administrator of a unix system. For deeper understanding of a variety of topics, O'Reilly & Associates is my favorite publisher. Their books are nearly always high quality, and are usually written by reputable sources, and occasionally by the actual creators of a tool. For example, the most famous Perl text is from O'Reilly and is called Programming Perl was written by Larry Wall, the creator of Perl. Homework for next week: Install Linux on a machine in the OCF. There will some crufty old 200MHz machines in front of the whiteboard. Use those rather than the gateways, the flatscreen monitors aren't supported by default in Linux yet, so it's not fun to use those, and besides, the guys that set those up might get annoyed. Install media will be in the desk drawers, feel free to install over eachother's installations. Configure as much as you want (networking, etc. is optional...), but definitely do the basic install. Below is a list of basic unix commands we think you should be familiar and comfortable with. These links can help you find information about commands you don't know already. You can also ask your peers, or an instructor. Some hints on getting more information and explanations about unix commands Google Search for "frequently used unix commands" LLNL's Quick Reference of Frequently used Unix Commands Very basic unix commands... ls cp, mv, rm chmod, chown, chgrp cd, pwd mkdir, rmdir, ln cat, more, less, head, tail man, apropos sort, uniq, wc, grep vi, pico, emacs date, cal pine, elm, mutt, mail telnet, rlogin, ssh ftp, scp w, who, finger, talk, nwrite hostname, whoami, set, history passwd, quota -v, du lpr, lp ps, kill find, locate, which exit redirection >, >>, <, | > send output to file: ls > directory-listing >> append output to end of file (don't overwrite file) < send a file as input to a command: mail friend < filename | send output of one command to input of next command: ls -la | more

Sources of information on using unix

The most used source of information on unix commands is the unix manual pages. E.g. to read the manpage for the ls command, you would type: "man ls". The manual pages are divided up into different sections. Since there are sections for unix commands and sections for the c programming language, and other sections for perl, sometimes the section that the man command will give you by default will not be for the command that you are looking for. E.g. for "less," on some OCF sun boxes, "man less" will return the manpage for a perl pragma (which is found in section 3 of the manpage - the section that is being drawn from is displayed in parentheses in the upper righthand corner along with the commandname (i.e. for less, it looks like "less(3)"), rather than for the unix command. The manpage for the unix command "less" is found the section 1 of the manual, so to get at that manpage, you would need to type "man -s1 less".

Here are some details about how unix man pages are written.
As a side note, the apropos command is useful for finding which section of the manual the page you are looking for resides. ("apropos less" finds all the manpages which mention the word less in their description.)

E.g. looking for less, we see there are two commands called less, which I've highlighted, one in section (1) and another in section (3).


% apropos less UNIVERSAL UNIVERSAL (3) - base class for ALL classes (blessed references) jpegtran jpegtran (1) - lossless transformation of JPEG files less less (3) - perl pragma to request less of something from the compiler min min (9f) - return the lesser of two integers less less (1) - opposite of more lesskey lesskey (1) - specify key bindings for less

Since the manpage for less from section 3 didn't give us what we wanted to see, this suggests we look at the less manpage in the other section ("man -s1 less", even though the description "opposite of more" doesn't really explain anything.

It's also important to know that your shell has built in commands which will probably not have manual pages of their own. For example "man set" on the OCF will find the command "set" for the TCL scripting language, which is probably not what you want. If you type "which set" you will be told that set is a built-in shell command. To read about the set command, you will need to look at the manpage for your shell (e.g. "man csh").

This brings us to the problem of knowing what shell you are using. The most common default shells are sh, csh, bash, and less likely, tcsh, zsh or ksh. You can check your processes and find out which shell you are using, e.g. "ps" will give you something like:

% ps PID TTY TIME CMD 10380 pts/4 0:00 tcsh 10362 pts/4 0:00 csh

In this case, the lower numbered PID (process ID) is the shell that the system gave me when I logged in, csh, and tcsh is a shell I ran later and am currently using. To find what the behavior of set would be in my current shell, tcsh, I would look at the tcsh manpage: "man tcsh".

Man pages can be difficult to read, an require some getting used to. You can find information about many commands online. Try a google search for "unix command foo" if the manpage is unhelpful to you.

There are some useful unix books out there. In particular the "Unix Power Tools" mentioned above and the O'Reilly & Associates "Unix in a Nutshell" is said to have a reasonable level of information about commands, while not being as confusing as a manpage.